Abstract: To avoid impact on the environment, facilities for permanent disposal of hazardous waste adopt multibarrier design schemes. As the primary barrier very often consists of cement-based materials, two distinct aspects are essential for the selection of suitable complementary barriers: (1) selective sorption of the contaminants in the repository and (2) long-term chemical stability in hyperalkaline concrete-derived media. A multidisciplinary approach combining experimental strategies from environmental chemistry and materials science is therefore essential to provide a reliable assessment of potential candidate materials. Chabazite is typically synthesized in 1 M KOH solutions but also crystallizes in simulated young cement pore water, a pH 13 aqueous solution mainly containing K+ and Na+ cations. Its formation and stability in this medium was evaluated as a function of temperature (60 and 85 °C) over a timeframe of more than 2 years and was also asessed from a mechanistic point of view. Chabazite demonstrates excellent cation-exchange properties in simulated young cement pore water. Comparison of its Cs+ cation exchange properties at pH 8 and pH 13 unexpectedly demonstrated an increase of the KD with increasing pH. The combined results identify chabazite as a valid candidate for inclusion in engineered barriers for concrete-based waste disposal.

Abstract: A new ordered mesoporous silica material (COK-19) with cubic symmetry is synthesized by silicate polycondensation in a citric acid/citrate buffered micellar solution of Pluronic F127 triblock copolymer near neutral pH. SAXS, nitrogen adsorption, TEM, and electron tomography reveal the final material has a cubic close packed symmetry (Fm3̅m) with isolated spherical mesopores interconnected through micropores. Heating of the synthesis medium from room temperature to 70 °C results in a mesopore size increase from 7.0 to 11.2 nm. Stepwise addition of the silicate source allows isolation of a sequence of intermediates that upon characterization with small-angle X-ray scattering uncovers the formation process via formation and aggregation of individual silica-covered Pluronic micelles.

Abstract: Gallium oxide nanorods with unprecedented small dimensions (20-80nm length and 3-5nm width) were prepared using a novel, template-free synthesis method. This nanomaterial is an excellent heterogeneous catalyst for the sustainable epoxidation of alkenes with H2O2, rivaling the industrial benchmark microporous titanosilicate TS-1 with linear alkenes and being much superior with bulkier substrates. A thorough characterization study elucidated the correlation between the physicochemical properties of the gallium oxide nanorods and their catalytic performance, and underlined the importance of the nanorod morphology for generating a material with high specific surface area and a high number of accessible acid sites.

Abstract: A new, single-step protocol for wrapping individual nanosized β-casein micelles with silica is presented. This biomolecule-friendly synthesis proceeds at low protein concentration at almost neutral pH, and makes use of sodium silicate instead of the common silicon alkoxides. This way, formation of potentially protein-denaturizing alcohols can be avoided. The pH of the citrate-buffered synthesis medium is close to the isoelectric point of β-casein, which favours micelle formation. A limited amount of sodium silicate is added to the protein micelle suspension, to form a thin silica coating around the β-casein micelles. The size distribution of the resulting proteinsilica structures was characterized using DLS and SAXS, as well as 1H NMR DOSY with a dedicated pulsed-field gradient cryo-probehead to cope with the low protein concentration. The degree of silica-condensation was investigated by 29Si MAS NMR, and the nanostructure was revealed by advanced electron microscopy techniques such as ESEM and HAADF-STEM. As indicated by the combined characterization results, a silica shell of 2 nm is formed around individual β-casein micelles giving rise to separate protein coresilica shell nanoparticles of 17 nm diameter. This alcohol-free method at mild temperature and pH is potentially suited for packing protein molecules into bio-compatible silica nanocapsules for a variety of applications in biosensing, therapeutic protein delivery and biocatalysis.

Abstract: IWW-type zeolite with Si/Ge of 4.9 is obtained using 5-azonia-spiro[4,4]nonane as template in fluoride-free medium under hydrothermal conditions at 175 °C. In an otherwise identical synthesis, using the related 5-azonia-spiro[4,5]decane as structure directing agent, a mixture of IWW and NON zeolite types was formed. In absence of GeO2 from the reactant mixture, pure NON formed. The IWW zeolite was characterized by XRD, SEM, and HRTEM. IWW zeolite displayed a unique morphology and could be calcined at 600 °C without loss of crystallinity. The Si/Ge ratio of the IWW zeolite was increased by postsynthesis modification. Part of the germanium could be eliminated from the as-synthesized IWW zeolite by acid leaching using 6 M HCl solution. Also the calcined material could be degermanated. Here the presence of a silicon source in the acidic leaching solution minimized structural damage. This way the Si/Ge ratio of the IWW zeolite was increased from 4.9 up to 10.

Abstract: We report on the design of nanosystems based on functionalized -Fe 2 O 3 nanostructures supported on fluorine-doped tin oxide (FTO) substrates. The target materials were developed by means of hybrid vapor phase approaches, combining plasma assisted-chemical vapor deposition (PA-CVD) for the production of iron(III) oxide systems and the subsequent radio frequency (RF)-sputtering or atomic layer deposition (ALD) for the functionalization with Au nanoparticles or TiO 2 overlayers, respectively. The interplay between material characteristics and the adopted processing parameters was investigated by complementary analytical techniques, encompassing X-ray photoelectron spectroscopy (XPS), field emission-scanning electron microscopy (FE-SEM), high angle annular dark field-scanning transmission electron microscopy (HAADF-STEM), and energy dispersive X-ray spectroscopy (EDXS). The obtained results highlight the possibility of fabricating Au/ -Fe 2 O 3 nanocomposites, with a controlled dispersion and distribution of metal particles, and TiO 2 / -Fe 2 O 3 heterostructures, characterized by an intimate coupling between the constituent oxides.

Abstract: Evolution of crystalline phases with temperature has been studied in materials produced by high-pressure high-temperature treatment of 9-borabicyclo[3.3.1]nonane dimer (9BBN), triphenylborane and trimesitylborane. The boron-doped diamond nanoparticles with a size below 10 nm were obtained at 8–9 GPa and temperatures 970–1250 °C from 9BBN only. Bridged structure and the presence of boron atom in the carbon cycle of 9BBN were revealed to be a key point for the direct synthesis of doped diamond nanocrystals. The diffusional transformation of the disordered carbon phase is suggested to be the main mechanism of the nanodiamond formation from 9BBN in the temperature range of 970–1400 °C. Aqueous suspensions of primary boron-doped diamond nanocrystals were prepared upon removal of non-diamond phases that opens wide opportunities for application of this new nanomaterial in electronics and biotechnologies.

Abstract: Photo-activated processes have been widely recognized as cost-effective and environmentally friendly routes for both renewable energy generation and purification/cleaning technologies. We report herein on a plasma- assisted approach for the synthesis of Fe 2 O 3 -TiO 2 nanosystems functionalized with Au nanoparticles. Fe 2 O 3 nanostructures were grown by plasma enhanced-chemical vapor deposition, followed by the sequential sputtering of titanium and gold under controlled conditions, and final annealing in air. The target nanosystems were subjected to a thorough multi-technique characterization, in order to elucidate the interrelations between their chemico-physical properties and the processing conditions. Finally, the functional performances were preliminarily investigated in both sunlight-assisted H 2 O splitting and photocatalytic activity tests in view of self- cleaning applications. The obtained results highlight the possibility of tailoring the system behaviour and candidate the present Fe 2 O 3 -TiO 2 -Au nanosystems as possible multi-functional low-cost platforms for light-activated processes.

Abstract: The electrodeposition of nickel nanostructures on glassy carbon was investigated in 1:2 choline chloride – urea (1:2 ChCl-U) deep eutectic solvent (DES). By combining electrochemical techniques with ex-situ FE-SEM, XPS, HAADF-STEM and EDX, the electrochemical processes occurring during nickel deposition were better understood. Special attention was given to the interaction between the solvent and the growing nickel nanoparticles. The application of a suffciently negative potential results into the electrocatlytic hydrolisis of residual water in the DES, which leads to the formation of a mixed layer of Ni/Ni(OH)2(ads). In addition, hydrogen bonds between hydroxide species and the DES components could be formed, quenching the growth of the nickel clusters favouring their aggregation. Due to these processes, a highly dense distribution of nickel nanostructures can be obtained within a wide potential range. Understanding the role of residual water and the interactions at the interface during metal electrodeposition from DESs is essential to produce supported nanostructures in a controllable way for a broad range of applications and technologies.

Abstract: Nanocomposites CoOx/SnO2 based on tin oxide powders with different crystallinity have been prepared by wet chemical synthesis and characterized in detail by ICP-MS, XPS, EPR, XRD, HAADF-STEM imaging and EDX-STEM mapping. It was shown that cobalt is distributed differently between the bulk and surface of SnO2 nanocrystals, which depends on the crystallinity of the SnO2 matrix. The measurements of gas sensor properties have been carried out during exposure to CO (10 ppm), and H2S (2 ppm) in dry air. The decrease of sensor signal toward CO was attributed to high catalytic activity of Co3O4 leading to oxidation of carbon monoxide entirely on the surface of catalyst particles. The formation of a p-CoOx/n-SnO2 heterojunction results in high sensitivity of nanocomposites in H2S detection. The conductance significantly changed in the presence of H2S, which was attributed to the formation of metallic cobalt sulfide and removal of the p – n junction.

Abstract: The electrodeposition of nickel nanostructures on glassy carbon was investigated in 1:2 choline chloride urea deep eutectic solvent (DES) containing different amounts of water. By combining electrochemical techniques, with ex situ field emission scanning electron microscopy, high-angle annular dark field scanning transmission electron microscopy, and energy-dispersive X-ray spectroscopy, the effect of water content on the electrochemical processes occurring during nickel deposition was better understood. At highly negative potentials and depending on water content, Ni growth is halted due to water splitting and formation of a mixed layer of Ni/NiOx(OH)(2(1-x)(ads)). Moreover, under certain conditions, the DES components can also be (electro)chemically reduced at the electrode surface, blocking further three-dimensional growth of the Ni NPs. Hence, a two-dimensional crystalline Ni-containing network can be formed in the interparticle region.

Abstract: The relationship between irrigation water availability and crop revenue is multifaceted. However, most of the previous studies focused only on the direct effect of irrigation water on crop revenue or considered that the indirect effect passes only through the farmers’ improved farm inputs usage. Nevertheless, unlike previous studies, this study argues that a one-sided argument that irrigation water directly causes high crop revenue or indirectly affects crop revenue only via the farmers’ improved farm inputs usage is incomplete, as irrigation water not only directly contributes to crop revenue but also indirectly conduces to crop revenue via both the type of crops produced and the farmers’ improved farm inputs usage. Considering the previous studies’ limitations, this study investigates pathways how small-scale irrigation water affects crop revenue and identifies challenges of small-scale irrigation farming in Fogera district, Ethiopia. Results endorsed that irrigation water has both direct and indirect effects on crop revenue. The indirect effect is 67 percent of the total effect and it is mediated by both the type of crops produced and farmers’ improved farm inputs usage. The result also indicated that irrigation user farmers have a higher income, more livestock assets and resources and better food, housing, and cloths than the non-users. Moreover, challenges related to agricultural output and input market were identified as the most severe problem followed by crop disease. The findings of our study suggest that to utilize the benefits of irrigation water properly, it is crucial to encourage farmers to use more improved farm inputs and to shift from staple to cash crop production. Moreover, farmers are frequently exposed to cheating by illegal brokers in the output market, therefore it is also important to increase farmers’ accessibility to output and input markets, the quality of improved farm inputs, and the bargaining power of farmers with market information.

Abstract: Good’s buffers can act both as nucleating and shape- directing agents during the synthesis of anisotropic gold nanostars (AuNS). Although different Good’s buffers can produce AuNS shapes with branches that are oriented along specific crystallographic directions, the mechanism is not fully understood. This paper reports how an analysis of the intermediate structures during AuNS synthesis from HEPES, EPPS, and MOPS Good’s buffers can provide insight into the formation of seedless AuNS. Electron tomography of AuNS structures quenched at early times (minutes) was used to characterize the morphology of the incipient seeds, and later times were used to construct the growth maps. Through this approach, we identified how the crystallinity and shape of the first structures synthesized with different Good’s buffers determine the final AuNS morphologies.

Abstract: Zeogrids and Zeotiles are hierarchical materials built from assembled MFI zeolite precursor units. Permanent secondary porosity in these materials is obtained through self assembly of nanoparticles encountered in MFI zeolite synthesis in the presence of supramolecular templates. Hereon, the aggregated species are termed nanoslabs. Zeogrids are layered materials with lateral spacings between nanoslabs creating galleries qualifying as supermicropores. Zeotiles present a diversity of tridimensional nanoslab assemblies with mesopores. Zeotile-1, -4 and -6 are hexagonal mesostructures. Zeotile-1 has triangular and hexagonal channels; Zeotile-4 has hexagonal channels interconnected via slits. Zeotile-2 has a cubic structure with gyroid type mesoporosity. The behavior of Zeogrids and Zeotiles in adsorption, membrane and chromatographic separation and catalysis has been characterized and compared with zeolites and mesoporous materials derived from unstructured silica sources. Shape selectivity was detected via adsorption of n- and iso-alkanes. The mesoporosity of Zeotiles can be exploited in chromatographic separation of biomolecules. Zeotiles present attractive separation properties relevant to CO2 sequestration. Because of its facile synthesis procedure without hydrothermal steps Zeogrid is convenient for membrane synthesis. The performance of Zeogrid membrane in gas separation, nanofiltration and pervaporation is reported. In the Beckmann rearrangement of cyclohexanone oxime Zeogrids and Zeotiles display a catalytic activity characteristic of silicalite-1 zeolites. Introduction of acidity and redox catalytic activity can be achieved via incorporation of Al and Ti atoms in the nanoslabs during synthesis. Zeogrids are active in hydrocracking, catalytic cracking, alkylation and epoxidation reactions. Zeogrids and Zeotiles often behave differently from ordered mesoporous materials as well as from zeolites and present a valuable extension of the family of hierarchical silicate based materials.